Dental crown and bridge structure.



G. L. WERNET & H. A. GOLLETT.

DENTAL GROWN AND BRIDGE STRUCTURE.

APPLICATION FILED 1120.19, 1911.

1,057,192, I Patented Mar.25,191 3.

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UNITED STATES PATENT OFFICE.

GEORGE L. WERNET AND HENRY A. COLLETT, OF PHILADELPHIA, PENNSYLVANIA.

DENTAL CROWN AND BRIDGE STRUCTURE.

To all whom it may concern:

Be it known that we, GEORGE L. VVERNET and HENRY A. CoLLE'rT, citizensof the United States, and residents of Philadelphia, county ofPhiladelphia, State of Pennsylvania, have invented certain new anduseful Improvements in Dental Crown and Bridge Structures, of which thefollowing is a specification.

Our invention relates to improvements in dental crown and bridgestructures and includes a new and novel improved construction of bridgefor supporting the teeth in the posterior part of the mouth, that is tosay, the molars and bicuspids, as well as of the teeth themselves.

One object of our invention is to combine the teeth and the bridge so asto produce such correlation of the two that the capacity of the teeth towithstand pressure during mastication or at other times is greatly increased.

Another object of our invention is to provide improved means whereby atooth, or crown, if broken, may be replaced with a new tooth or crownwithout the necessity of removing the bridge from the mouth.

A further object of our invention is to provide a construction in whichthe direction of greatest strength of the bridge is substantially in theplane of the greatest stress or force impressed upon the bridge duringmastication whereby the practical strength of the bridge is materiallyenhanced.

It is also an object of our invention to so construct the teeth that thestrain thereon is in substantial alinement with the direction ofgreatest length thereof where it is the strongest and to secure theteeth to the bridge in such relation thereto that the thinner portionsthereof which are subjected to pressure and strain are supportedimmediately by portions of the bridge.

A still further object of our invention is to secure the teeth upon thebridge in such relation to the latter that the bridge is not visibleexcept upon the lingual side. And it is also an object of our inventionto provide a construction in which the interior surface of the structureis smooth, substantially straight and without the presence of shouldersor crevices of any kind or character.

Another object of our-invention is to divide and balance the stressesupon the inner Specification of Letters Patent.

Application filed December 19, 1911.

Patented Mar. 25, 1913. Serial No. 666,685.

portion of the crown of the tooth so as to remove these stresses fromthe outer portion of the tooth and support them fully upon the bridge ortooth backing.

Another object of our invention is to form, facing wedge shaped surfaces.of the bridge or tooth backing and a suitable ledge, at different acuteangles to the direction of strain upon the tooth crown, and to rest theinner portion of the tooth crown upon the wedge shaped recess thusformed.

Another object of our invention is to construct a bridge support ofgeneral band form with the greatest width of the band extended nearlythe length of the tooth, sloping enough to form an effective support tothe teeth yet nearly enough in line with the direction of pressure uponthe tooth crown to obtain the advantage of pressure nearly in line withthe width of the band.

Other objects and advantages of our invention will be referred tohereinafter in the detailed portion of the specification or will beapparent therefrom.

In the accompanying drawing we have illustrated convenient embodimentsof our invention which have proved practical, in-

expensive and generally desirable, but it will be understood thatchanges in the de tails of construction may be made Within the scope ofthe claims without departing from our said invention.

In the drawings:Figure 1 is an elevation of the inside surface of abridge having teeth secured and supported thereon and embodying ourinvention; Fig. 2 is a transverse section thereof on the line 22 of Fig.1; Fig. 3 is an inside view of a tooth constructed in accordance withour invention; and Fig. 4 is a transverse section corresponding to thatshown in Fig. 2 but showing a modified construction.

In the forms which we have illustrated, the bridge 1 is provided at oneend with an anchoring pin 2 which is secured or anchored to a naturaltooth in any known manner; that is tosay, the pin 2 is connected to thebase portion (not shown) of a cup-like part 3 in which is seated anartificial tooth 4. The lower end of such part is hollow and is adaptedto fit over the upper end of a natural tooth which is prefrom each otherand from the anchoring or supporting means at its opposite ends as shownat 7 in Fig. 1 of the drawing. In proportion to its width the bridge isrelatively very thin, as is shown in Fig. 2 of the drawings. It will beobserved by reference to Fig. 2 that the bridge in the direction of itswidth is located and extends in a plane inclined inwardly or linguallyfrom the .vertical plane of the posterior teeth, that is, the bicuspidsand the molars. The direction of the principal stresses and strains uponthe bridge during mastication is substantially in the direction of theplane of its width, since it approximates a band and is nearly enough inthe plane of the strains due to mastication to have great stiffness. Theresult is that although a bridge may be constructed relatively very thinit has the requisite strength for all practical purposes. This is animportant consideration because it enablesa manufacturer to construct asatisfactory bridge with a minimum amount of metal which metal usuallyis gold or some other very expensive. substance.

The convex sides of the portions 6 are provided withrelatively wide, lowprojections or bosses 8 which form ledges 8 and which have convexsurfaces as shown at 9. These projections or bosses may be of anydesired shape or contour. From these bosses or projections 8 pins 10project. The ledge 8 forms a wedge shaped surface sloping oppositely tothe outer surface of the bridge or tooth support and these twooppositely sloping faces balance the strains due to mastication upon theinner edge of the crown and prevent transmission of these strains to theouter part of the tooth. One purpose of the bosses or projections 9 andthe pins 10 is to provide a satisfactory means for anchoring, securingand supporting the artificial teeth upon the bridge or support.

The teeth 15 embodying our invention are provided respectively upontheir lingual sides with concavities 16 which are formed to fit snuglyand closely the convex surfaces of the portions 6 of the bridge 1. Nearthe central portions of the respective concavities 16 we form a shallowdepression 17 the bottom of which is of the same curvature as that ofthe surface 9 of the boss or projection 8 and we also provide therespective teeth with holes 18 for the reception of the pins 10. It willbe understood that the shape of the shallow depressions or cavities 17is the same as that of the bosses or projections 8.

Preferably, and as illustrated, the pins 8 extend substantially at rightangles to the curved surfaces of the portions 7 and the bosses orprojections 8. That is to say, the said pins are extended in an outwardor a buccal direction and are inclined upwardly at a small angle to ahorizontal plane through the bridge.

It will be observed upon inspection of Fig. 2 that the upper edge of thebridge terminates or is located a short distance below the top or crownof the tooth and that the inside or lingual surface of the tooth isflush with the adjoining surface of the upper lingual side of the tooth.It will also be observed that the lower projecting ends of the portions6 terminate at points very near the lower ends of the teeth 15 and thatthe adjacent inside lingual surfaces of the latter are flush with thelingual surface of the said portions 6. Bythis arrangement we secure atooth as well as a dental bridge structure in which the surfaces aresmooth and are entirely free from projecting parts forming shoulders andare also entirely free from crevices in which food may lodge and,remaining in the mouth, become very offensive and objectionable. Inother words, our invention provides a construction which may be readilycleansed by washing, which is a most desirable feature of dental bridgeconstruction. It will also be observed, upon reference particularly toFig. 2 of the drawing, that the metallic part of the bridge proper isentirely concealed and hidden from view by the over-lying teeth 15 andthe teeth are so supported that the vertical stresses thereon due to theforce employed during mastication of food are in directions extendingsubstantially in the direction of the length of the teeth. It will alsobe observed that the inside upper portions of the teeth, which arerelatively thin, are supported directly and immediately by the uppercurved portion of the bridge and the ledge and also that the shouldersor ledges formed between the body of the bridge and the bosses orprojections 8 are strong enough to form most effective abutments toresist the strains and stresses to which the respecgrally with eachother. In Fig. 4, however, the bridge 20 is formed separately from theboss 21 and the pin 22 and the said boss and pin are shown as consistingof different material from the bridge proper. From an economical pointof view the latter construction may be preferable because it permits theuse of a base metal for the boss and the pin. Base metal may be employedfor these parts for the reason that they do not at any time come intocontact with the saliva and acid secretions which are or may be presentin the mouth. In both forms of construction the teeth are placed inposition upon the bridge over the pins and bosses or projections, asillustrated in Figs. 2 and 4, and are firmly secured thereto by means ofany suitable dental cement, as indicated at 23.

In case a tooth should he accidentally or otherwise broken, it isapparent that it may be replaced by a new tooth without interfering withadjoining teeth and without removal of the bridge from the mouth.

A tooth constructed to embody our invention, one form of which isillustrated in the drawings, is well adapted for crown work for therepair of a natural tooth, for the reason that when such a tooth isemployed its support is upon the lingual side of the tooth and thereforeinvisible from the exterior of the mouth. By reason of this fact thecompleted structure presents a par ticularly neat appearance.

Having thus described our invention, we claim 1. In a dental bridgestructure, the combination of a bridge having portions provided withconvex surfaces upon their buccal sides and having bosses formed uponthe said surfaces and pins projecting from said bosses with teeth havingdepressions formed upon the lingual sides thereof which fit snugly thesaid convex surfaces and the said teeth having cavities therein for thereception of the said bosses and pins upon the said convex surfaces.

2. In a dental bridge structure, the combination of a bridge with teethsecured to forming an acute angle to the line of direction of pressureupon the tooth, a ledge projecting from the support whose surface formsan acute angle with the line of direction of pressure upon the toothcrown the two surfaces forming a wedge shaped space between them, incombination with a porcelain facing having its inner crown portionseated within this wedge shaped space.

4. In a device of the character described, a lingual facing for a toothforming a support therefor, which facing is provided with an outwardprojection forming a ledge and with a pin extending outwardly from saidprojection, all in combination with a tooth mounted on said facing bymeans of said projectionand pin.

5. A11 artificial tooth having a depression formed upon its lingual sidewhich depression extends from a point adjacent to the inner edge of thecusp of the tooth to a point adjacent to the lower end of the said toothand the said tooth being provided with a cavity which extends outwardlyand at an acute angle to a line substantially normal to the cusp surfaceof the tooth.

In testimony that we claim the foregoing as our invention, we havehereunto signed our names this 18th day of December, A. D.

GEORGE L. WERNET. HENRY A. GOLLETT. In the presence of GEo. H. WEIDNER,CYRUs N. ANDERSON.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

